When balancer fails to find a node to balance drained tablets into, it
throws an exception with tablet id and node id, but it's also good to
know more details about the balancing state that lead to failure
refs: #19504
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
(cherry picked from commit c3d9831c5f)
Closesscylladb/scylladb#19619
Tests will rely on that, they will run in shuffle mode, and disable
balancing around section which otherwise would be infinitely blocked
by ongoing shuffling (like repair).
(cherry picked from commit 1513d6f0b0)
In order to avoid per-table tablet load imbalance balance from forming
in the cluster after adding nodes, the load balancer now picks the
candidate tablet at random. This should keep the per-table
distribution on the target node similar to the distribution on the
source nodes.
Currently, candidate selection picks the first tablet in the
unordered_set, so the distribution depends on hashing in the unordered
set. Due to the way hash is calculated, table id dominates the hash
and a single table can be chosen more often for migration away. This
can result in imbalance of tablets for any given table after
bootstrapping a new node.
For example, consider the following results of a simulation which
starts with a 6-node cluster and does a sequence of node bootstraps
and decommissions. One table has 4096 tablets and RF=1, and the other
has 256 tablets and RF=2. Before the patch, the smaller table has
node overcommit of 2.34 in the worst topology state, while after the
patch it has overcommit of 1.65. overcommit is calculated as max load
(tablet count per node) dividied by perfect average load (all tablets / nodes):
Run #861, params: {iterations=6, nodes=6, tablets1=4096 (10.7/sh), tablets2=256 (1.3/sh), rf1=1, rf2=2, shards=64}
Overcommit : init : {table1={shard=1.03, node=1.00}, table2={shard=1.51, node=1.01}}
Overcommit : worst: {table1={shard=1.23, node=1.10}, table2={shard=9.85, node=1.65}}
Overcommit (old) : init : {table1={shard=1.03, node=1.00}, table2={shard=1.51, node=1.01}}
Overcommit (old) : worst: {table1={shard=1.31, node=1.12}, table2={shard=64.00, node=2.34}}
The worst state before the patch had the following distribution of tablets for the smaller table:
Load on host ba7f866d...: total=171, min=1, max=7, spread=6, avg=2.67, overcommit=2.62
Load on host 4049ae8d...: total=102, min=0, max=6, spread=6, avg=1.59, overcommit=3.76
Load on host 3b499995...: total=89, min=0, max=4, spread=4, avg=1.39, overcommit=2.88
Load on host ad33bede...: total=63, min=0, max=3, spread=3, avg=0.98, overcommit=3.05
Load on host 0c2e65dc...: total=57, min=0, max=3, spread=3, avg=0.89, overcommit=3.37
Load on host 3f2d32d4...: total=27, min=0, max=2, spread=2, avg=0.42, overcommit=4.74
Load on host 9de9f71b...: total=3, min=0, max=1, spread=1, avg=0.05, overcommit=21.33
One node has as many as 171 tablets of that table and another one has as few as 3.
After the patch, the worst distribution looks like this:
Load on host 94a02049...: total=121, min=1, max=6, spread=5, avg=1.89, overcommit=3.17
Load on host 65ac6145...: total=87, min=0, max=5, spread=5, avg=1.36, overcommit=3.68
Load on host 856a66d1...: total=80, min=0, max=5, spread=5, avg=1.25, overcommit=4.00
Load on host e3ac4a41...: total=77, min=0, max=4, spread=4, avg=1.20, overcommit=3.32
Load on host 81af623f...: total=66, min=0, max=4, spread=4, avg=1.03, overcommit=3.88
Load on host 4a038569...: total=47, min=0, max=2, spread=2, avg=0.73, overcommit=2.72
Load on host c6ab3fe9...: total=34, min=0, max=3, spread=3, avg=0.53, overcommit=5.65
Most-loaded node has 121 tablets and least loaded node has 34 tablets.
It's still not good, a better distribution is possible, but it's an improvement.
Refs #16824
(cherry picked from commit 3be6120e3b)
(cherry picked from commit c9bcb5e400)
(cherry picked from commit 7b1eea794b)
(cherry picked from commit 603abddca9)
Refs #18885Closesscylladb/scylladb#19036
* github.com:scylladb/scylladb:
tablets: load balancer: Use random selection of candidates when moving tablets
test: perf: Add test for tablet load balancer effectiveness
load_sketch: Extract get_shard_minmax()
load_sketch: Allow populating only for a given table
... and replace it with boolean enable_tablets option. All the places
in the code are patched to check the latter option instead of the former
feature.
The option is OFF by default, but the default scylla.yaml file sets this
to true, so that newly installed clusters turn tablets ON.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
(cherry picked from commit 83d491af02)
Closesscylladb/scylladb#19012
In order to avoid per-table tablet load imbalance balance from forming
in the cluster after adding nodes, the load balancer now picks the
candidate tablet at random. This should keep the per-table
distribution on the target node similar to the distribution on the
source nodes.
Currently, candidate selection picks the first tablet in the
unordered_set, so the distribution depends on hashing in the unordered
set. Due to the way hash is calculated, table id dominates the hash
and a single table can be chosen more often for migration away. This
can result in imbalance of tablets for any given table after
bootstrapping a new node.
For example, consider the following results of a simulation which
starts with a 6-node cluster and does a sequence of node bootstraps
and decommissions. One table has 4096 tablets and RF=1, and the other
has 256 tablets and RF=2. Before the patch, the smaller table has
node overcommit of 2.34 in the worst topology state, while after the
patch it has overcommit of 1.65. overcommit is calculated as max load
(tablet count per node) dividied by perfect average load (all tablets / nodes):
Run #861, params: {iterations=6, nodes=6, tablets1=4096 (10.7/sh), tablets2=256 (1.3/sh), rf1=1, rf2=2, shards=64}
Overcommit : init : {table1={shard=1.03, node=1.00}, table2={shard=1.51, node=1.01}}
Overcommit : worst: {table1={shard=1.23, node=1.10}, table2={shard=9.85, node=1.65}}
Overcommit (old) : init : {table1={shard=1.03, node=1.00}, table2={shard=1.51, node=1.01}}
Overcommit (old) : worst: {table1={shard=1.31, node=1.12}, table2={shard=64.00, node=2.34}}
The worst state before the patch had the following distribution of tablets for the smaller table:
Load on host ba7f866d...: total=171, min=1, max=7, spread=6, avg=2.67, overcommit=2.62
Load on host 4049ae8d...: total=102, min=0, max=6, spread=6, avg=1.59, overcommit=3.76
Load on host 3b499995...: total=89, min=0, max=4, spread=4, avg=1.39, overcommit=2.88
Load on host ad33bede...: total=63, min=0, max=3, spread=3, avg=0.98, overcommit=3.05
Load on host 0c2e65dc...: total=57, min=0, max=3, spread=3, avg=0.89, overcommit=3.37
Load on host 3f2d32d4...: total=27, min=0, max=2, spread=2, avg=0.42, overcommit=4.74
Load on host 9de9f71b...: total=3, min=0, max=1, spread=1, avg=0.05, overcommit=21.33
One node has as many as 171 tablets of that table and the one has as few as 3.
After the patch, the worst distribution looks like this:
Load on host 94a02049...: total=121, min=1, max=6, spread=5, avg=1.89, overcommit=3.17
Load on host 65ac6145...: total=87, min=0, max=5, spread=5, avg=1.36, overcommit=3.68
Load on host 856a66d1...: total=80, min=0, max=5, spread=5, avg=1.25, overcommit=4.00
Load on host e3ac4a41...: total=77, min=0, max=4, spread=4, avg=1.20, overcommit=3.32
Load on host 81af623f...: total=66, min=0, max=4, spread=4, avg=1.03, overcommit=3.88
Load on host 4a038569...: total=47, min=0, max=2, spread=2, avg=0.73, overcommit=2.72
Load on host c6ab3fe9...: total=34, min=0, max=3, spread=3, avg=0.53, overcommit=5.65
Most-loaded node has 121 tablets and least loaded node has 34 tablets.
It's still not good, a better distribution is possible, but it's an improvement.
Refs #16824
(cherry picked from commit 603abddca9)
This is needed, because the same name cannot be used for 2 separate
entities, because we're getting double-metrics-registration error, thus
the names have to be configurable, not hardcoded.
Intra-node migrations are scheduled for each node independently with
the aim to equalize per-shard tablet count on each node.
This is needed to avoid severe imbalance between shards which can
happen when some table grows and is split. The inter-node balance can
be equal, so inter-node migration cannot fix the imbalance. Also, if
RF=N then there is not even a possibility of moving tablets around to
fix the imbalance. The only way to bring the system to balance is to
move tablets within the nodes.
After scheduling inter-node migrations, the algorithm schedules
intra-node migrations. This means that across-node migrations can
proceed in parallel with intra-node migrations if there is free
capacity to carry them out, but across-node migrations have higher
priority.
Fixes#16594
Currently the load balancer is only generting an inter-node plan, and
the algorithm is embedded in make_plan(). The method will become even
harder to follow once we add more kinds of plan generating steps,
e.g. inter-node plan. Extract the inter-node plan to make it easier to
add other plans and see the grand flow.
target nodes
The node_load datastructure was not updated to reflect migration
decisions on the target node. This is not needed for inter-node
migration because target nodes are not considered as sources. But we
want it to reflect migration decisions so that later inter-node
migration sees an accurate picture with earlier migrations reflected
in node_load.
Finalization of tablet split was only synchronizing with migrations, but
that's not enough as we want to make sure that all processes like repair
completes first as they might hold erm and therefore will be working
with a "stale" version of token metadata.
For synchronization to work properly, handling of tablet split finalize
will now take over the state machine, when possible, and execute a
global token metadata barrier to guarantee that update in topology by
split won't cause problems. Repair for example could be writing a
sstable with stale metadata, and therefore, could generate a sstable
that spans multiple tablets. We don't want that to happen, therefore
we need the barrier.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Closesscylladb/scylladb#18380
before this change, we rely on the default-generated fmt::formatter
created from operator<<, but fmt v10 dropped the default-generated
formatter.
in this change, we include `fmt/ranges.h` and/or `fmt/std.h`
for formatting the container types, like vector, map
optional and variant using {fmt} instead of the homebrew
formatter based on operator<<.
with this change, the changes adding fmt::formatter and
the changes using ostream formatter explicitly, we are
allowed to drop `FMT_DEPRECATED_OSTREAM` macro.
Refs scylladb#13245
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
This PR fixes a problem with replacing a node with tablets when
RF=N. Currently, this will fail because tablet replica allocation for
rebuild will not be able to find a viable destination, as the replacing node
is not considered to be a candidate. It cannot be a candidate because
replace rolls back on failure and we cannot roll back after tablets
were migrated.
The solution taken here is to not drain tablet replicas from replaced
node during topology request but leave it to happen later after the
replaced node is in left state and replacing node is in normal state.
The replacing node waits for this draining to be complete on boot
before the node is considered booted.
Fixes https://github.com/scylladb/scylladb/issues/17025
Nodes in the left state will be kept in tablet replica sets for a while after node
replace is done, until the new replica is rebuilt. So we need to know
about those node's location (dc, rack) for two reasons:
1) algorithms which work with replica sets filter nodes based on their location. For example materialized views code which pairs base replicas with view replicas filters by datacenter first.
2) tablet scheduler needs to identify each node's location in order to make decisions about new replica placement.
It's ok to not know the IP, and we don't keep it. Those nodes will not
be present in the IP-based replica sets, e.g. those returned by
get_natural_endpoints(), only in host_id-based replica
sets. storage_proxy request coordination is not affected.
Nodes in the left state are still not present in token ring, and not
considered to be members of the ring (datacanter endpoints excludes them).
In the future we could make the change even more transparent by only
loading locator::node* for those nodes and keeping node* in tablet replica sets.
Currently left nodes are never removed from topology, so will
accumulate in memory. We could garbage-collect them from topology
coordinator if a left node is absent in any replica set. That means we
need a new state - left_for_real.
Closesscylladb/scylladb#17388
* github.com:scylladb/scylladb:
test: py: Add test for view replica pairing after replace
raft, api: Add RESTful API to query current leader of a raft group
test: test_tablets_removenode: Verify replacing when there is no spare node
doc: topology-on-raft: Document replace behavior with tablets
tablets, raft topology: Rebuild tablets after replacing node is normal
tablets: load_balancer: Access node attributes via node struct
tablets: load_balancer: Extract ensure_node()
mv: Switch to using host_id-based replica set
effective_replication_map: Introduce host_id-based get_replicas()
raft topology: Keep nodes in the left state to topology
tablets: Introduce read_required_hosts()
This fixes a problem with replacing a node with tablets when
RF=N. Currently, this will fail because new tablet replica allocation
will not be able to find a viable destination, as the replacing node
is not considered a candidate. It cannot be a candidate because
replace rolls back on failure and we cannot roll back after tablets
were migrated.
The solution taken here is to not drain tablet replicas from replaced
node during topology request but leave it to happen later after the
replaced node is left and replacing node is normal.
The replacing node waits for this draining to be complete on boot
before the node is considered booted.
Fixes#17025
This series adds notification before dropping views and indices so that the
tablet_allocator can generate mutations to respectively drop all tablets associated with them from system.tablets.
Additional unit tests were added for these cases.
Note that one case is not yet tested: where a table is allowed to be dropped while having views that depend on it, when it is dropped from the alternator path.
This is tested indirectly by testing dropping a table with live secondary index as it follows the same notification path as views in this series.
Fixes#17627Closesscylladb/scylladb#17773
* github.com:scylladb/scylladb:
migration_manager: notify before_drop_column_family when dropping indices
schema_tables: make_update_indices_mutations: use find_schema to lookup the view of dropped indices
migration_manager: notify before_drop_column_family before dropping views
cql-pytest: test_tablets: add test_tablets_are_dropped_when_dropping_table
tablet_allocator: on_before_drop_column_family: remove unused result variable
Call the before_drop_column_family notifications
before dropping the views to allow the tablet_allocator
to delete the view's tablets.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Currently load balancer skips nodes only based on its "administrative"
state, i.e. whether it's drained/decommissioned/removed/etc. There's no
way to exclude any node from balancing decision based on anything else.
This patch add this ability by adding skiplist argument to
balance_tablets() method. When a node is in it, it will not be
considered, as if it was removenode-d.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
The new stage will be used to revert migration that fails at some
stages. The goal is to cleanup the pending replica, which may already
received some writes by doing the cleanup RPC to the pending replica,
then jumping to "revert_migration" stage introduced earlier.
If pending node is dead, the call to cleanup RPC is skipped.
Coordinators use old replicas.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
It's like end_migration, but old replicas intact just removing the
transition (including new replicas).
Coordinators use old replicas.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Commit 904bafd069 consolidated the two
existing for_each_tablet() overloads, to the one which has a future<>
returning callback. It also added yields to the bodies of said
callbacks. This is unnecessary, the loop in for_each_tablet() already
has a yield per tablet, which should be enough to prevent stalls.
This patch is a follow-up to #17118Closesscylladb/scylladb#17284
The table query param is added to get the describe_ring result for a
given table.
Both vnode table and tablet table can use this table param, so it is
easier for users to user.
If the table param is not provided by user and the keyspace contains
tablet table, the request will be rejected.
E.g.,
curl "http://127.0.0.1:10000/storage_service/describe_ring/system_auth?table=roles"
curl "http://127.0.0.1:10000/storage_service/describe_ring/ks1?table=standard1"
Refs #16509Closesscylladb/scylladb#17118
* github.com:scylladb/scylladb:
tablets: Convert to use the new version of for_each_tablet
storage_service: Add describe_ring support for tablet table
storage_service: Mark host2ip as const
tablets: Add for_each_tablet_gently
get0() dates back from the days where Seastar futures carried tuples, and
get0() was a way to get the first (and usually only) element. Now
it's a distraction, and Seastar is likely to deprecate and remove it.
Replace with seastar::future::get(), which does the same thing.
`available_shards` could be negative when `resize_plan` is empty, and
the loop to build `resize_plan` stops at the next iteration after
`available_shards` is assigned with a negative number. so, instead of
making it an `unsigned`, let's just compare it using `std::cmp_less()`.
this change should silence following warning:
```
/home/kefu/.local/bin/clang++ -DDEBUG -DDEBUG_LSA_SANITIZER -DFMT_DEPRECATED_OSTREAM -DFMT_SHARED -DSANITIZE -DSCYLLA_BUILD_MODE=debug -DSCYLLA_ENABLE_ERROR_INJECTION -DSEASTAR_API_LEVEL=7 -DSEASTAR_DEBUG -DSEASTAR_DEBUG_PROMISE -DSEASTAR_DEBUG_SHARED_PTR -DSEASTAR_DEFAULT_ALLOCATOR -DSEASTAR_LOGGER_COMPILE_TIME_FMT -DSEASTAR_LOGGER_TYPE_STDOUT -DSEASTAR_SCHEDULING_GROUPS_COUNT=16 -DSEASTAR_SHUFFLE_TASK_QUEUE -DSEASTAR_SSTRING -DSEASTAR_TYPE_ERASE_MORE -DXXH_PRIVATE_API -DCMAKE_INTDIR=\"Debug\" -I/home/kefu/dev/scylladb -I/home/kefu/dev/scylladb/build/gen -I/home/kefu/dev/scylladb/seastar/include -I/home/kefu/dev/scylladb/build/seastar/gen/include -I/home/kefu/dev/scylladb/build/seastar/gen/src -g -O0 -g -gz -std=gnu++20 -fvisibility=hidden -Wall -Werror -Wextra -Wno-error=deprecated-declarations -Wimplicit-fallthrough -Wignored-qualifiers -Wno-c++11-narrowing -Wno-mismatched-tags -Wno-overloaded-virtual -Wno-unsupported-friend -Wno-enum-constexpr-conversion -Wno-unused-parameter -Wno-missing-field-initializers -Wno-deprecated-copy -Wno-ignored-qualifiers -ffile-prefix-map=/home/kefu/dev/scylladb=. -march=westmere -U_FORTIFY_SOURCE -Werror=unused-result "-Wno-error=#warnings" -fstack-clash-protection -fsanitize=address -fsanitize=undefined -fno-sanitize=vptr -MD -MT service/CMakeFiles/service.dir/Debug/tablet_allocator.cc.o -MF service/CMakeFiles/service.dir/Debug/tablet_allocator.cc.o.d -o service/CMakeFiles/service.dir/Debug/tablet_allocator.cc.o -c /home/kefu/dev/scylladb/service/tablet_allocator.cc
/home/kefu/dev/scylladb/service/tablet_allocator.cc:529:60: error: comparison of integers of different signs: 'long' and 'const size_t' (aka 'const unsigned long') [-Werror,-Wsign-compare]
529 | if (resize_plan.size() > 0 && available_shards < size_desc.shard_count) {
| ~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~
```
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
When load balancer emits finalize request, the coordinator will
now react to it by splitting each tablet in the current tablet
map and then committing the new map.
There can be no active migration while we do it.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
This implements the ability in load balancer to emit split or merge
requests, cancel ongoing ones if they're no longer needed, and
also finalize those that are ready for the topology changes.
That's all based on average tablet size, collected by coordinator
from all nodes, and split and merge thresholds.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
New tablet replicas are allocated and rebuilt synchronously with node
operations. They are safely rebuilt from all existing replicas.
The list of ignored nodes passed to node operations is respected.
Tablet scheduler is responsible for scheduling tablet rebuilding transition which
changes the replicas set. The infrastructure for handling decommission
in tablet scheduler is reused for this.
Scheduling is done incrementally, respecting per-shard load
limits. Rebuilding transitions are recognized by load calculation to
affect all tablet replicas.
New kind of tablet transition is introduced called "rebuild" which
adds new tablet replica and rebuilds it from existing replicas. Other
than that, the transition goes through the same stages as regular
migration to ensure safe synchronization with request coordinators.
In this PR we simply stream from all tablet replicas. Later we should
switch to calling repair to avoid sending excessive amounts of data.
Fixes https://github.com/scylladb/scylladb/issues/16690.
Closesscylladb/scylladb#16894
* github.com:scylladb/scylladb:
tests: tablets: Add tests for removenode and replace
tablets: Add support for removenode and replace handling
topology_coordinator: tablets: Do not fail in a tight loop
topology_coordinator: tablets: Avoid warnings about ignored failured future
storage_service, topology: Track excluded state in locator::topology
raft topology: Introduce param-less topology::get_excluded_nodes()
raft topology: Move get_excluded_nodes() to topology
tablets: load_balancer: Generalize load tracking
tablets: Introduce get_migration_streaming_info() which works on migration request
tablets: Move migration_to_transition_info() to tablets.hh
tablets: Extract get_new_replicas() which works on migraiton request
tablets: Move tablet_migration_info to tablets.hh
tablets: Store transition kind per tablet
There are currently two options how to "request" the number of initial tables for a table
1. specify it explicitly when creating a keyspace
2. let scylla calculate it on its own
Both are not very nice. The former doesn't take cluster layout into consideration. The latter does, but starts with one tablet per shard, which can be too low if the amount of data grows rapidly.
Here's a (maybe temporary) proposal to facilitate at least perf tests -- the --tablets-initial-scale-factor option that enhances the option number two above by multiplying the calculated number of tablets by the configured number. This is what we currently do to run perf tests by patching scylla, with the option it going to be more convenient.
Closesscylladb/scylladb#16919
* github.com:scylladb/scylladb:
config: Add --tablets-initial-scale-factor
tablet_allocator: Add initial tablets scale to config
tablet_allocator: Add config
New tablet replicas are allocated synchronously with node
operations. They are safely rebuilt from all existing replicas.
The list of ignored nodes passed to node operations is respected.
Tablet scheduler is responsible for scheduling tablet transition which
changes the replicas set. The infrastructure for handling decommission
in tablet scheduler is reused for this.
Scheduling is done incrementally, respecting per-shard load
limits. Rebuilding transitions are recognized by load calculation to
affect all tablet replicas.
New kind of tablet transition is introduced called "rebuild" which
adds new tablet replica and rebuilds it from existing replicas. Other
than that, the transition goes through the same stages as regular
migration to ensure safe synchronization with request coordinators.
In this PR we simply stream from all tablet replicas. Later we should
switch to calling repair to avoid sending excessive amounts of data.
Fixes#16690.
This patch removes some duplication of logic and implicit assumptions
by creating clear algebra for load impact calculation and its
application to state of the load balancer.
Will make adding new kinds of tablet transitions with different impact
on load much easier.
When allocating tablets for table for the frist time their initial count
is calculated so that each shard in a cluster gets one tablet. It may
happen that more than one initial tablet per shard is better, e.g. perf
tests typically rely on that.
It's possible to specify the initial tablets count when creating a
keyspace, this number doesn't take the cluster topology into
consideration and may also be not very nice.
As a temporary solution (e.g. for perf tests) we may add a configurable
that scales the initial number of calculated tablets by some factor
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Tablet allocator is a sharded service, that starts in main, it's worth
equipping it with a config. Next patches will fill it with some payload
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
The name of the keyspace being part of the partition key is not useful,
the table_id already uniquely identifies the table. The keyspace name
being part of the key, means that code wanting to interact with this
table, often has to resolve the table id, just to be able to provide the
keyspace name. This is counter productive, so make the keyspace_name
just a static column instead, just like table_name already is.
Fixes: #16377Closesscylladb/scylladb#16881
Now all the callers have it at hands (spoiler: not yet initialized, but
still) so the params can also have it.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Previous patch added params to r.s. classes' constructors, but callers
don't construct those directly, instead they use the create_r.s.()
wrapper. This patch adds params to the wrapper too.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Load balancing needs to be disabled before making a series of manual
migrations so that we don't fight with the load balancer.
Also will be used in tests to ensure tablets stick to expected locations.
After adding the keyspace_metadata parameter to
migration_listener::on_before_create_column_family,
tablet_allocator doesn't need to load it from the database.
This change is necessary before merging migration_manager::announce
calls in the following commit.
After adding the new prepare_new_column_family_announcement that
doesn't assume the existence of a keyspace, we also need to get
rid of the same assumption in all on_before_create_column_family
calls. After all, they may be initiated before creating the
keyspace. However, some listeners require keyspace_metadata, so we
pass it as a new parameter.
This reverts commit 4b80130b0b, reversing
changes made to a5519c7c1f. It's suspected
of causing dtest failures due to a bug in coroutine::parallel_for_each.
After adding the keyspace_metadata parameter to
migration_listener::on_before_create_column_family,
tablet_allocator doesn't need to load it from the database.
This change is necessary before merging migration_manager::announce
calls in the following commit.
